In ectotherms, temperature is important as an environmental cue and as a rate-limiting factor in controlling all aspects of reptilian life processes. The parietal eye and pineal body (e-2 epiphyseal system) participate in the control and selection of optimal environmental temperatures and, thus, secondarily affect reptilian physiology and behavior. This project examines the levels of body temperature which permit the expression of species-typical behavior and physiology (reproduction) in animals lesioned during and after neonatal development. The presence of melatonin in alligators which lack pineals raises the possibility that melatonin is not characteristic of pineals and that pineal bodies do not fulfill the definition of an endocrine gland.